A semiconductor light emitting device is provided, which does not deteriorate in luminance, maintains a high reliability, permits more free choice of an adhesive, and promises effective extraction of light to the exterior even when it is bonded to a lead frame or other support with the adhesive in practical use. In a GaN light emitting diode, GaN compound semiconductor layers are stacked sequentially on a front surface of a sapphire substrate to form a light emitting diode structure, and a reflective film is formed on a rear surface. Alternatively, the GaN compound semiconductor layers forming the light emitting diode structure are selectively removed by etching to define an inverted mesa-shaped end surface, and the reflective film is formed on the end surface. Both the p-side electrode and the n-side electrode are formed on a common side of the substrate where the GaN compound semiconductor layers are formed.